Current DNA detection and sequencing technologies are based primarily on placing DNA targets on substrates such as grids or arrays so that the identities of DNAs are recognized through their location on the substrates. Even in the cases that nanoballs are used in DNA sequencing, these nanoballs are used as carriers for DNA amplification and the amplified DNAs along with nanoballs are still placed on patterned substrates.
Therefore, there are needs in the field to continue to develop new ways for DNA amplification and detection without the necessity of or dependence on substrate. Further, current technology often depends on a limited number of differentiable signals for DNA sequencing, for example, only utilizing 4 different fluorescent colors to code the 4 individual nucleotides, such as in Illumina's sequence by synthesis technology, and in Pacific Biosciences' SMRT technology. Sometimes, the detection signal is only based on one type of signal, for example, the chemiluminescent signal from the pyrosequencing of 454 sequencing technology. These existing technologies only sequence DNA one base by one base, including when the electronic signal is utilized as in the nanopore based sequencing and when the pH change is utilized as in the ion torrent technology. Hence, a method to enable DNA sequencing through longer base steps could be highly beneficial to improve sequencing accuracy, reduce sequencing time, reduce cost, and increase throughput.